This invention relates to the press fitting of machine parts into bores or onto shafts.
When press fitting a part into a bore or onto a shaft having a surface that stops movement of the fitted part relative to the receiving part, it is impossible to check the quality of the press fit by simply measuring the force applied by a ram after the part has come to rest against the stop surface because the measured reaction force would rise excessively immediately on reaching the stop surface.
In the case of machine parts which are subject to high stresses and vibrations during their operation, it is important that the quality of the press fit should conform to a prescribed standard so that the machine part will not accidentally become detached during operation. The pressing of valve seat rings made of steel into bores that are sized to receive the rings in a cylinder head made of aluminum in an internal combusion engine is an example where the ability to check the quality of the press fit is vital.